The user self-service tools of SAP HANA extended application services, classic user self-service, a part of SAP HANA Database versions 1.00 and 2.00, can be misused to enumerate valid and invalid user accounts. An unauthenticated user could use the error messages to determine if a given username is valid.
https://launchpad.support.sap.com/#/notes/2549983
https://blogs.sap.com/2017/12/12/sap-security-patch-day-december-2017/